Stalled D-47 fermentation

I have a D-47 fermentation going on a key lime mead and it is stalling out at a higher sg than I would like. We're at about week seven now, and the point drop per day is not measurable now.

Original sg 1.125, current sg 1.034 (target sg say 1.015-1.120)

I'm just using test strips, but I measure the pH at 3.3 (I've added ~10 oz of lime juice to the primary fermentation)

Temp now 71 deg F (was fermenting at 62-65 deg F, but now summer is here. Could get the temp down by putting it in water with a fan...)

So what can I do to get it to ferment another 10-15 gravity points down?

In a previous D-47 key lime batch with og 1.130 it fermented to sg 1.023, and the pH was no higher than 3.3, so I'd think maybe I can goose the yeasts into a little more activity. But I've read that the yeasts don't really use nutrients or oxygen late in the secondary fermentation. Similarly re-pitching D-47 into almost 12% abv seems optimistic. So I don't really know what I can do to goose the fermentation along 10-15 more points with the D-47 yeast.

Or I was thinking of pitching some 1118 (or V1116??), but then I don't want the batch to ferment past sg 1.015, and if pitching with champaign yeast is too successful maybe I will not be able to arrest the fermentation. Also I wanted to age on the D-47 lees, but if there is also 1118 lees in there then maybe this wouldn't be such a good idea..

-"We're at about week seven". Well yeah a fermentation usually takes 2-3 weeks so...no doubt you are having problems.

You can repitch just not directly, you need to restart the ferment.

Please post the recipe with more accuracy. What is the total volume? what did you add to the mead? what type of honey? ammount of yeast? rehydrated? nutrient schedule? buffer?
The fact that you added 10oz of lime juice tells us little without the total volume. Im guessing its 5 gals but no clue. However it does seem a lot of juice for a pH of 3.3

" But I've read that the yeasts don't really use nutrients or oxygen late in the secondary fermentation" Unless im missing something this is primary fermentation. And you are right about the oxigen, but wrong about the nutrients. Dont add anything with DAP, but you can add some fermaid O or some boiled yeast.

Either boil some yeast, add it, and put the batch in a hotter place (this might produce some off flavours, degass daily), and this MIGHT help you chew some points, or go to page 28-29http://www.scottlab.com/pdf/ScottlabsHandbook2016.pdf
And follow steps 3-12 (IGNORE STEPS 1 AND 2. If you dont have goferm its ok). You can use D47 or EC-1118/K1V

"I don't want the batch to ferment past sg 1.015" Well... if you pitch either D47 or EC1118 again and you do it well (as the handbook says), it will go past that most likely.

"Also I wanted to age on the D-47 lees, but if there is also 1118 lees in there then maybe this wouldn't be such a good idea.." Why are there ec1118 lees there? If its because when it was getting stuck you added some yeast, dont worry about them, you can sur lie age.

Well, there's the long way (especially for 5 or 6 gallons). Using new yeast, create a 2 liter starter, once you get active fermentation, start feeding it the must from your stalled fermentation. At some point you'll have 50 percent of your must in two different containers, you can either let the one that is active go dry and then blend them together or keep feeding the one that's active.

You definitely need to do something about temperature control. Sounds like you already know that D47 likes to stay below 68 degrees. What most of us forget is that a fermenting must can be 5 to 10 degrees warmer than the ambient temperature. So while you saying the temperature in your house is 71 degrees, your must could be 76 to 81 degrees. :-(

If you can't control temperature and you want to make mead during the summer, you're best to stick with yeasts that are more tolerant of higher temperatures.

Thank you Dadux and Darigoni- yes apologies it is a 5 gal batch. It was never a super-vigorous fermentation (maxed at about 2 points a day drop in week two), but I've been using Fermaid O exclusively and mellow fermentations have been my experience with this. I originally pitched using the ScottLabs protocol for rehydrating dry yeast.

I will follow your advice (and the Scott Labs directions) and get a new fermentation going and add the stalled must to that.

I'll use D-47 again with the hope of keeping it all D47 for aging on lees.

Thank you Dadux and Darigoni- yes apologies it is a 5 gal batch. It was never a super-vigorous fermentation (maxed at about 2 points a day drop in week two), but I've been using Fermaid O exclusively and mellow fermentations have been my experience with this. I originally pitched using the ScottLabs protocol for rehydrating dry yeast.

I will follow your advice (and the Scott Labs directions) and get a new fermentation going and add the stalled must to that.

I'll use D-47 again with the hope of keeping it all D47 for aging on lees.

Wish me luck! And thanks again

No problem. I'd encourage you to review your numbers for the nutrients (7 weeks looks like ages to me, sincerely. So maybe the nutrients or maybe something else in the process, but thats not normal 2, 3 or eve 4 weeks yeah sure, but 7 is a lot) and drop the lime next time. You can always add it when the ferment is over, with similar or same results.

I'm doing a traditional, with D47, and the OG ended up being higher than I planned (1.132). So, when it started slowing down to 2 points a day, and I was sitting at 1.050, I thought I might be in trouble, so diluted it with spring water to 1.040. It's been fermenting at 4 points a day since, so it looks like I'll get down to reasonable final gravity.

I thought the fermentation was doing ok, not great, but ok at 2 pts/day then about 1.5 pts/day. But after week three I transferred to glass carboy and then left on vacation for a month, so I don't know when the ferment fizzled out. I followed the TOSNA regime for the Fermaid O, for "low YAN requirement" yeasts.

I agree the lime juice in the primary creates a harsher environment for the yeast. But again, I made a previous batch with lime juice and D-47 with the exact same parameters, and it fermented through 107 sg points, so I thought this would be ok for a repeat.

I thought the fermentation was doing ok, not great, but ok at 2 pts/day then about 1.5 pts/day. But after week three I transferred to glass carboy and then left on vacation for a month, so I don't know when the ferment fizzled out. I followed the TOSNA regime for the Fermaid O, for "low YAN requirement" yeasts.

I agree the lime juice in the primary creates a harsher environment for the yeast. But again, I made a previous batch with lime juice and D-47 with the exact same parameters, and it fermented through 107 sg points, so I thought this would be ok for a repeat.

Well I've never used TOSNA but i have used TiOSNA and with D47 too. And It has never gone that slow. My ferments chew early on 10-20 points per day. Sure, with TOSNA/TiOSNA is usually not that fast (but can be) but still 10 points per day is normal. And well i might be wrong but i dont think a healthy ferment should take that long... Just my 2 cents. Something weird for me there. Dont know what, but something was not right. In other cases my bets would be lack of nutrients (could be if the calc was wrong but im gonna asume it was not that) or pH (you said its not that), so i dont really know. Aereating? underpitching? temp shock? problems with rehydration? dunno. Maybe it IS normal, but not in my experience...nor have i read about 7 week long ferments that were doing fine (except wild ferments maybe).

For reference, my D47 TiOSNA ferment took 16 days i think, for 112 points.

In your previous batch did it ferment to dryness? or did it end sweet? D47 can go further than 107. Maybe that was a stuck ferment too, just stuck at a lower gravity for whatever reason.

Oh interesting! Thanks for your observations. I've been brewing the mead about a year and a half now (probably about 8-10 small batches now of two gallons each, and only now the 5 gal batches), and I always used FermaidO. My fermentations have always have been slow, and I suspected that FermaidK would give a more vigorous fermentation. Wonder if it is the difference between FermaidO and FermaidK, or if it is me?!

Maybe I'll brew a little 2 gal batch with FermaidK, and keep everything else the same, just to see what happens.

Anyone else have input on how vigorous a fermentation they get from FermaidO vs FermaidK?!

[edit] - Oh- my previous D-47 fermentation ended sweet too, but that was the goal. I tried to estimate where the yeast would hit its alcohol tolerance (the expected sg drop), and then went over that og by the amount of residual sugar I wanted. But I screwed up the nutrient schedule with that batch, so it may not be the best example of how things should go..

Oh interesting! Thanks for your observations. I've been brewing the mead about a year and a half now (probably about 8-10 small batches now of two gallons each, and only now the 5 gal batches), and I always used FermaidO. My fermentations have always have been slow, and I suspected that FermaidK would give a more vigorous fermentation. Wonder if it is the difference between FermaidO and FermaidK, or if it is me?!

Maybe I'll brew a little 2 gal batch with FermaidK, and keep everything else the same, just to see what happens.

Anyone else have input on how vigorous a fermentation they get from FermaidO vs FermaidK?!

[edit] - Oh- my previous D-47 fermentation ended sweet too, but that was the goal. I tried to estimate where the yeast would hit its alcohol tolerance (the expected sg drop), and then went over that og by the amount of residual sugar I wanted. But I screwed up the nutrient schedule with that batch, so it may not be the best example of how things should go..

Sure, K might be faster, but you also add half the ammount of nutrients than in O.
I dont know, it could be, but I've read other people's thread when using O and it didnt take so long, or start so slow. Maybe go to the meadlog or seach for Ferimaid O recipes.

Oh interesting! Thanks for your observations. I've been brewing the mead about a year and a half now (probably about 8-10 small batches now of two gallons each, and only now the 5 gal batches), and I always used FermaidO. My fermentations have always have been slow, and I suspected that FermaidK would give a more vigorous fermentation. Wonder if it is the difference between FermaidO and FermaidK, or if it is me?!

Maybe I'll brew a little 2 gal batch with FermaidK, and keep everything else the same, just to see what happens.

Anyone else have input on how vigorous a fermentation they get from FermaidO vs FermaidK?!

[edit] - Oh- my previous D-47 fermentation ended sweet too, but that was the goal. I tried to estimate where the yeast would hit its alcohol tolerance (the expected sg drop), and then went over that og by the amount of residual sugar I wanted. But I screwed up the nutrient schedule with that batch, so it may not be the best example of how things should go..

You never did say how much yeast you are pitching for a 5 gallon batch?

For the D-47 5-gal batch (actually at pitch it was 5.25 gal) I pitched 8g D-47, rehydrated in 10g GoFerm in 200ml water at the recommended temperatures. I had one step of atemperation before pitching the starter into the must.

I did have 6oz lime juice in the must already at pitch. I measured it at pH~3.6 with test strips. OG 1.025

I also pitched Ka11 yeast into 5 gals of the same must. This fermentation maxed at a 7pts/day drop around day 4 and then backed off to about 4pts/day. But this fermented down to 1.015 sg which was the target.